Hydrogen fuel cell vehicles sales appear to be on the rise as more than 5,500 units were sold since they were launched — a number that is expected to top 6,000 units by the end of 2017, according to Information Trends.

The market research firm based its data on a report entitled: “Hydrogen Fuel Cell Vehicles: A Global Analysis,” which revealed that nearly 2,400 of the vehicles were sold in the first three quarters of the year.

The sales activity is considered to be unusual due to the lack of a widely available, “robust” hydrogen fueling infrastructure, according to Naqi Jaffery, the lead author of the report.

“By 2021, at least 10 brands will be selling hydrogen fuel cell vehicles,” he said in a news release. “By this time, hydrogen fuelling infrastructures will be sufficiently developed in several regions to allow large-scale hydrogen mobility.”

Carmakers Toyota, Lexus, Hyundai, Kia, Honda, Mercedes-Benz and BMW, along with Tata Motors, Pininfarina S.p.A. (owned by Mahindra & Mahindra) and Riversimple will all be competing for market share by 2021.

Toyota’s Mirai has already garnered three quarters of hydrogen fuel cell sales in the market, with the Hyundai ix35 Tucson Fuel Cell and Honda Clarity Fuel Cell sharing the rest.

As for which countries appear to be selling the most vehicles, the U.S. and Canada have generated 50 per cent of the global hydrogen fuel cell vehicle sales so far and Europe has managed 10 per cent, according to the news release.

Europe has captured a smaller share of the market because its hydrogen stations are spread across 15 countries rather than being concentrated in one state like the U.S. The other 40 per cent of global sales are spread between Japan and Korea.